1. Field of the Invention
This invention relates to a new polyvinylidene fluoride composition improved by the presence of a fluoroelastomer. This invention is particularly directed to a composition which, when formed into a finished article provides the finished article with improved notch impact toughness and elongation at rupture. This invention is particularly concerned with improving the impact strength and elongation at rupture characteristics of polyvinylidene fluoride products.
2. DISCUSSION OF THE PRIOR ART
Polyvinylidene fluoride (PVF.sub.2) has been used in the fabrication of many articles, including articles employed as chemical apparatuses, for example. It is known that polyvinylidene fluoride is characterized by good thermal, electrical and chemical properties. However, while the thermal and the chemical properties of polyvinylidene fluoride as a rule, satisfy the requirements that have been made therefor, in a number of special applications the mechanical characteristics are inadequate. Thus, it has been found that the mechanical characteristics in respect of notch impact toughness and elongation at rupture of polyvinylidene fluoride finished articles are insufficient.
It would be possible to improve these characteristics by internal or external plasticizing. However, when a plasticized is added to a polyvinylidene fluoride composition there is observed the impairment of other properties, such as tensile strength, thermal stability of shape or chemical resistance. Therefore, the use of internal or external plasticizers to improve the notch impact toughness and elongation at rupture of polyvinylidene articles, is not a practical approach.
It therefore became desirable to provide an improved polyvinylidene fluoride composition which when formed into a finished polyvinylidene fluoride article would impart to that article improved notch impact toughness and improved elongation at rupture. It became particularly desirable to provide a new polyvinylidene fluoride composition which would not materially alter the otherwise good thermal stability of shape, tensile strength and chemical resistance of the polyvinylidene fluoride finished article.